1. Field of the Invention
The present invention relates to elastic wave devices including a plurality of elastic wave element portions, such as duplexers, and to manufacturing methods for such elastic wave devices.
2. Description of the Related Art
Elastic wave devices have thus far been widely used as duplexers in cellular phones. For example, Japanese Unexamined Patent Application Publication No. 2010-98551 discloses a duplexer including an elastic wave element portion that configures a transmission filter and an elastic wave element portion that configures a reception filter, disposed on the same piezoelectric substrate. In Japanese Unexamined Patent Application Publication No. 2010-98551, a shield electrode is provided between a portion having the transmission filter and a portion having the reception filter.
According to the duplexer disclosed in Japanese Unexamined Patent Application Publication No. 2010-98551, a shield electrode is formed between the transmission filter and the reception filter. Doing so suppresses electromagnetic field coupling from occurring between the transmission filter and the reception filter. This is intended to improve isolation characteristics.
However, although the shield electrode is provided in the duplexer disclosed in Japanese Unexamined Patent Application Publication No. 2010-98551, the resulting structure still cannot sufficiently suppress the electromagnetic field coupling, and thus the isolation characteristics are still insufficient.